IP International Journal of Aesthetic and Health Rejuvenation

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Botulinum toxin for writer`s cramp patients: A study with multi-channel EMG

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Original Article

Author Details : Venkateshwarla Rama Raju*

Volume : 3, Issue : 4, Year : 2020

Article Page : 89-92

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Abstract

Injection with Botulinum toxin in the dystonic muscles of writer’s cramp is the most effective therapeutic treatment (method) available today for the other movement disorders such as dystonia. Botulinum toxin is a protein produced by the bacterium Clostridium botulinum. It is the most toxic protein known with an LD50 of roughly 0.005-0.05 µg/kg. It was noted in 1950s that injecting overactive muscles with minute quantities of botulinum toxin type-A would cause a decreased muscle activity by blocking the release of acetylcholine at the neuromuscular junction, thereby rendering the muscle unable to contract for a period of 3 to 4 months. 12 Writer`s cramp patients included in this study and their prognostic analysis are experimentally diagnosed and the analysis are given under.

Twelve patients with writer’s cramp (8 with concordant and 4 with discordant MMs) were assessed. On comparison of the measures of dispersion; D group had statistically significant difference between LHWS and RHWS (variance, standard deviation and F ratio) with a larger variance in RHWS, as compared to C group where variances and SD were equal or smaller in the RHWS compared to LHWS. Mean amplitudes for RHWS and LHWS for the same muscles, though differ significantly in statistical terms, showed a consistent pattern only in the fifth muscle with a larger mean amplitude on left side in all patients and were not of value in differentiating between concordant (C) and discordant (D) groups of patients. The principal component (PC) scores of the 12 patients showed 80% variance in our computation in the scatter plot diagram. The cluster analysis based on dissimilarity among the patients' signals show a possibility that, in addition to the grouping of patients as C or D, some other groupings may also be meaningful. EMG-EMG coherence was assessed in the Writer’s cramp hand muscles, namely ECR, ECU, FCR, FCU, followed by 5^th muscle. The coherence computed, evaluated and compared between flexor aspect of forearm and extensor aspect of intrinsic hand muscles was showed significant coherence in both groups. These observations suggest that the nature of EMG-EMG coherence in dystonia writer’s cramp may be constrained by the descending motor systems, both in terms of their anatomical distribution and their frequency characteristics. This study showed significant quantifiable EMG differences in the signals seen while writing with the right and left hands between those writer’s cramp patients with concordant mirror movements (C group) versus those with discordant mirror movements (D group). This was mainly seen in the measures of dispersion of the signal i.e., standard dispersion, variances and their ratio (F-ratio). These were statistically significantly different between the two groups, C and D, and the pattern of differences were consistent with the hypothesis that the discordant group had a compensatory force which overcame the dystonic force resulting in the final abnormal posture. This was seen in the form of larger variances and standard differences in the RHWS in the D group as compared to the C group, as the dystonic and compensatory forces both contribute to the instability. These differences were robust and seen in every measure of dispersion, such as in the patterns of significance of f-values for ratios of variances. Cluster analysis and more sophisticated analyses using advanced multivariate techniques leading to effective data summarization and measures of dissimiliarity between patients as reflected in the signals recorded and consequent possible clustering among them, however, did not lead to any meaningful clinical conclusions. These analyses could possibly be applied to longitudinal follow-ups and correlations with a normal control population in future to better comprehend the phenomenon of Writer’s cramp.

Keywords: ECR, ECU, FCR, FCU.

How to cite : Raju V R, Botulinum toxin for writer`s cramp patients: A study with multi-channel EMG. Int J Aesthet Health Rejuvenation 2020;3(4):89-92

Copyright © 2020 by author(s) and Int J Aesthet Health Rejuvenation. This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License (creativecommons.org)